Heating, ventilating and air conditioning (hvac) system for recreational vehicles

ABSTRACT

An HVAC unit for a recreational vehicle includes an enclosure having an ambient air inlet, an exterior outlet, a return air duct connection, and a conditioned air duct connection. An air conditioning system and a heating system are each located within the enclosure. The air conditioning system includes a compressor, a condenser, an expansion device, and an evaporator operably connected for cooling air entering the enclosure through the return air duct connection. The heating system includes a gas-fired burner assembly located within a sealed combustion chamber and a heat exchanger operably connected to the combustion chamber for heating air entering the enclosure through the a return air duct connection. A control system is operably connected to the air conditioning system and the heating system to selectively heat or cool air entering the enclosure through the a return air duct connection and exiting through the conditioned air duct connection.

CROSS-REFERENCE TO RELATED APPLICATIONS

Not Applicable

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

Not Applicable

REFERENCE TO MICROFICHE APPENDIX

Not Applicable

FIELD OF THE INVENTION

The field of the present invention generally relates to heating, ventilating and air conditioning (HVAC) systems and, more particularly, to HVAC systems for recreational vehicles and the like.

BACKGROUND OF THE INVENTION

Recreational vehicles and other similar type vehicles typically have air conditioning systems to maintain a controlled comfortable condition in the vehicle by cooling air within the vehicle. An external air conditioning unit is typically mounted on the roof of the recreational vehicle and houses all of the mechanical components of the air conditioning system. The external air conditioning unit has supply and return duct connections for connecting the external air conditioning unit with an interior air distribution and control system. For example, see U.S. Pat. Nos. 5,791,156 and 6,339,934, the disclosures of which are expressly incorporated herein in their entireties.

Recreational vehicles and other similar type vehicles also typically have furnace or heating systems to maintain a controlled comfortable condition in the vehicle by heating air within the vehicle. A furnace unit is typically mounted beneath the floor of the recreational vehicle and houses all of the mechanical components of the heating system. The furnace unit has supply and return duct connections for connecting the furnace unit with an interior air distribution and control system. For example, see U.S. Pat. No. 6,719,207, the disclosure of which is expressly incorporated herein in its entirety.

While the external air conditioning units may be generally effective, they are relatively inefficient when there is a sun load on the condenser. Additionally, the external air conditioning units are not very aesthetically pleasing to the overall exterior appearance of the vehicle. Moreover, the total HVAC systems are relatively expensive to produce and maintain. Accordingly, there is a need in the art for improved HVAC systems for recreational vehicles.

SUMMARY OF THE INVENTION

The present invention provides a HVAC system for a recreational vehicle which overcomes at least some of the above-noted problems of the related art. According to an embodiment described herein, a heating, ventilating, and air conditioning unit for a recreational vehicle comprises, in combination, an enclosure having an ambient air inlet, an exterior outlet, a return air duct connection, and a conditioned air duct connection, an air conditioning system for cooling air, and a heating system for heating air. The air conditioning system is located within the enclosure and includes a compressor, a condenser operably connected to the compressor, an expansion device operably connected to the condenser, and an evaporator operably connected to the expansion device and the compressor for cooling air entering the enclosure through the return air duct connection. The heating system is located within the enclosure and includes a gas-fired burner assembly located within a sealed combustion chamber and a heat exchanger operably connected to the combustion chamber for heating air entering the enclosure through the a return air duct connection. A control system operably connected to the air conditioning system and the heating system to selectively heat or cool air entering the enclosure through the a return air duct connection and exiting the enclosure through the conditioned air duct connection.

According to another embodiment described herein, a heating, ventilating, and air conditioning unit for a recreational vehicle comprises, in combination, an air conditioning system for cooling air, a heating system for heating air, a first fan positioned to draw ambient air in through an ambient air inlet, over the condenser, and out through an exterior outlet, a second fan positioned to draw return air in through a return air duct connection, over the evaporator and the heat exchanger, and out through a conditioned air duct connection, and an electric motor operably connected to both the first fan and the second fan for rotating both the first fan and the second fan. The air conditioning system includes a compressor, a condenser operably connected to the compressor, an expansion device operably connected to the condenser, and an evaporator operably connected to the expansion device and the compressor for cooling air. The heating system includes a gas-fired burner assembly located within a sealed combustion chamber and a heat exchanger operably connected to the combustion chamber for heating air entering the enclosure. A control system is operably connected to the air conditioning system, the heating system, and the electric motor to selectively heat or cool air entering the enclosure through the a return air duct connection and exiting the enclosure through the conditioned air duct connection.

According to yet another embodiment described herein, a heating, ventilating, and air conditioning unit for a recreational vehicle comprises, in combination, an enclosure having an ambient air inlet, an exterior outlet, a return air duct connection, and a conditioned air duct connection, an air conditioning system for cooling air, a heating system for heating air, a first fan positioned to draw ambient air in through an ambient air inlet, over the condenser, and out through an exterior outlet, a second fan positioned to draw return air in through a return air duct connection, over the evaporator and the heat exchanger, and out through a conditioned air duct connection, and an electric motor operably connected to both the first fan and the second fan for rotating both the first fan and the second fan. The air conditioning system is located within the enclosure and includes a compressor, a condenser operably connected to the compressor, an expansion device operably connected to the condenser, and an evaporator operably connected to the expansion device and the compressor for cooling air entering the enclosure through the return air duct connection. The heating system is located within the enclosure above the air conditioning system and includes a gas-fired burner assembly located within a sealed combustion chamber and a heat exchanger operably connected to the combustion chamber for heating air entering the enclosure through the a return air duct connection. A control system is operably connected to the air conditioning system and the heating system to selectively heat or cool air entering the enclosure through the a return air duct connection and exiting the enclosure through the conditioned air duct connection. A thermostat is operably connected to the control system to generally maintain air within the recreational vehicle at a desired temperature.

From the foregoing disclosure and the following more detailed description of various preferred embodiments it will be apparent to those skilled in the art that the present invention provides a significant advance in the technology and art of HVAC systems for recreational vehicles. Particularly significant in this regard is the potential the invention affords for providing a high quality, reliable, efficient, and relatively small HVAC unit. Additional features and advantages of various preferred embodiments will be better understood in view of the detailed description provided below.

BRIEF DESCRIPTION OF THE DRAWINGS

These and further features of the present invention will be apparent with reference to the following description and drawings, wherein:

FIG. 1 is a perspective view of an HVAC unit for a recreational vehicle according to the present invention, wherein components are removed and or transparent for clarity;

FIG. 2 is a front or outboard elevational view of the HVAC unit of FIG. 1;

FIG. 3 is a top plan view of the HVAC unit of FIGS. 1 and 2;

FIG. 4 is a rear or inboard elevational view of the HVAC unit of FIGS. 1 to 3;

FIG. 5 is a left side elevational view of the HVAC unit of FIGS. 1 to 4;

FIG. 6 is a right side elevational view of the HVAC unit of FIGS. 1 to 5;

FIG. 7 is a schematic view of a control system of the HVAC unit of FIGS. 1 to 6; and

FIG. 8 is a schematic view of air flow in the HVAC unit of FIGS. 1 to 7.

It should be understood that the appended drawings are not necessarily to scale, presenting a somewhat simplified representation of various preferred features illustrative of the basic principles of the invention. The specific design features of HVAC systems for recreational vehicles as disclosed herein, including, for example, specific dimensions, orientations, locations, and shapes will be determined in part by the particular intended application and use environment. Certain features of the illustrated embodiments have been enlarged or distorted relative to others to facilitate visualization and clear understanding. In particular, thin features may be thickened, for example, for clarity or illustration. All references to direction and position, unless otherwise indicated, refer to the orientation of the powered adjustable seat assembly illustrated in the drawings. In general, up or upward refers to an upward direction within the plane of the paper in FIG. 2 and down or downward refers to a downward direction within the plane of the paper in FIG. 2. Also in general, fore or forward refers to a direction out of the plane of the paper in FIG. 2 and aft or rearward refers to a direction into the plane of the paper in FIG. 2.

DETAILED DESCRIPTION OF CERTAIN PREFERRED EMBODIMENTS

It will be apparent to those skilled in the art, that is, to those who have knowledge or experience in this area of technology, that many uses and design variations are possible for the improved heating, ventilating and air conditioning (HVAC) systems disclosed herein. The following detailed discussion of various alternative and preferred embodiments will illustrate the general principles of the invention with reference to a preferred embodiment of a heating, ventilating and air conditioning (HVAC) systems for a recreational vehicle. The term “recreational vehicle” as use in the specification and claims is intended to include all vehicles in which a person at least temporarily camps or lives such as recreational vehicles (RVs), motor homes, travel trailers, campers, mobile homes, and the like. Other embodiments suitable for other applications will be apparent to those skilled in the art given the benefit of this disclosure.

Referring now to the drawings, FIGS. 1 to 7 show heating, ventilating and air conditioning (HVAC) Unit 10 for a recreational vehicle 12 according to a preferred embodiment of the present invention. The illustrated HVAC unit 10 includes an enclosure 14 having an ambient air inlet 16, an exterior outlet 18, a return air inlet or duct connection 20, and a conditioned air outlet or duct connection 22, an air conditioning or cooling system 24 for cooling air and located within the enclosure 14, a furnace or heating system 26 for heating air and located within the enclosure 14, and a control system 28 operably connected to the air conditioning system 24 and the heating system 26 to selectively heat or cool air entering the enclosure 14 through the a return air duct connection 20 and exiting the enclosure 14 through the conditioned air duct connection 22.

The illustrated enclosure 14 is generally rectangular-shaped and includes a base or bottom wall 30, an outboard or forward end wall 32, an inboard or rear end wall 34, opposed left and right side walls 36, 38, and a top wall 40. The illustrated enclosure 14 is substantially compact and sized and shaped to be mounted below a floor of the recreational vehicle 12 with the outboard wall 32 at an exterior side wall 44 of the recreational vehicle 12. The illustrated outboard wall 32 is provided with a peripheral flange 46 for engaging the exterior side wall 44 of the recreational vehicle 12. Preferably at least one of the walls is removable and/or provided with access doors or panels to selectively provide access to components located within the enclosure 14 as described in more detail hereinafter.

The illustrated ambient air inlet 16 is located in the outboard end wall 32 of the enclosure 14 at a bottom portion of the outboard end wall 32. The ambient air inlet 16 is in communication with exterior ambient air beside the recreational vehicle 12 so that exterior ambient air can be pulled into the HVAC unit 10. The illustrated ambient air inlet 16 is provided with a grate 48 to reduce the entry of unwanted debris. The illustrated exterior outlet 18 is located in the bottom wall 30 of the enclosure 13 near a forward portion of the enclosure 14. The exterior outlet 18 is in communication with exterior ambient air below the recreational vehicle 12 so that air can be released from the HVAC unit 10 toward the roadway. The illustrated return air duct connection 20 is located in the inboard end wall 34 of the enclosure 14 opposite the outboard end 32 wall at a bottom portion of the inboard end wall 34. The return duct connection 20 is connectable to a return air duct 50 of the recreational vehicle 12 to form a pathway for air within an interior space 52 of the recreational vehicle 12 to travel to the return air duct connection 22 of the HVAC unit 10. The illustrated conditioned air duct connection 22 is located in the inboard end wall 34 at an upper portion of the inboard end wall 34 and above the return air duct connection 20. The conditioned air duct connection 22 is connectable to a conditioned air duct 54 of the recreational vehicle 12 to form a pathway for conditioned air within HVAC unit 10 to return to the interior space 52 of the recreational vehicle 12.

The illustrated air conditioning system 24 is located within the enclosure 14 and includes a compressor 56, a condenser 58 operably connected to the compressor 56, an expansion device 60 operably connected to the condenser 58, and an evaporator 62 operably connected between the expansion device 60 and the compressor 56 for cooling air entering the enclosure 14 through the return air duct connection 22. The components of the air conditioning system 24 are connected by suitable refrigerant lines to form a cooling circuit in a known manner. The illustrated condenser and evaporator 58, 62 are fin and tube type devices but it is noted that any other suitable type of condenser or evaporator can alternatively be utilized.

The illustrated heating system 26 is located within the enclosure 14 above the air conditioning system 24 and includes a gas-fired burner assembly 64 located within a sealed combustion chamber 66, a fuel or gas inlet line 68 operably connecting a fuel source to the burner assembly 64, an electric fan or blower assembly 70 for drawing air into the combustion chamber 66, a heat exchanger 72 operably connected to the combustion chamber 66 for heating air entering the enclosure 14 through the a return air duct connection 20, and a flue gas outlet duct 74 for discharging combustion gases to the exterior space about the recreational vehicle 12. The illustrated burner assembly 64 and combustion chamber 66 is located at the top of the forward portion of the enclosure 14. The burner assembly 64 can be of any suitable type for burning a desired fuel to generate heat. The illustrated burner assembly 64 is adapted to burn liquefied petroleum gas (LPG) or propane but any other suitable fuel can alternatively used such as, for example, natural gas. The illustrated burner assembly 64 includes an electric igniter 75. The illustrated gas inlet line 68 extends through the right side wall 38 to the burner assembly 64. An electro-mechanical valve 76 is provided to selectively close and open the inlet line 68. The illustrated blower assembly 70 draw air from within the enclosure 14 that has entered through the ambient air inlet to the combustion chamber 66. The blower assembly 70 can be of any suitable type and is sized to draw a suitable amount of air to the sealed combustion chamber 66 to provide a desired pressure level within the sealed pressure chamber 66. The illustrated heat exchanger 72 rearwardly extends from the combustion chamber 66 and is located at the top of the ear portion of the enclosure 14. The illustrated heat exchanger 72 is of the tube type but can alternatively be of any other suitable type. The illustrated flue gas outlet duct 74 forwardly extends to the outboard wall 32 and in communication with the exterior space about the recreational vehicle 12.

Suitable baffles are provided within the enclosure 14 to form first and second chambers or air passages as described in more detail hereinbelow. The first chamber is formed at the forward portion of the enclosure 14 and houses the condenser 58 of the air conditioning system 24 and is in communication with the ambient air inlet 16 and the exterior outlet 18. The second chamber is formed at the rear portion of the enclosure 14 and houses the evaporator 62 of the air conditioning system 24 and the heat exchanger 72 of the heating system 26 and is in communication with the return air duct connection 20 and the conditioned air duct connection 22.

An air movement system is provided for moving air in each of the first and second chambers. A first fan or blower 78 is located within the first chamber at a front portion of the enclosure 14. The first fan 78 is sized and positioned so that, when operating, it draws ambient air into the enclosure 14 through the ambient air inlet 16 and over the condenser 58 of the air conditioning system 24. Air within the first chamber exits the enclosure 14 through the exterior outlet 18. It is noted that when the heating system 26 is operating, a portion of the air within the first chamber is drawn into the combustion chamber 66 by the combustion blower assembly 70. A second fan or blower 80 is located within the second chamber at a rear portion of the enclosure 14. The second fan 80 is sized and positioned so that, when operating, it draws ambient air into the enclosure 14 through the return air duct connection 20, over the evaporator 62 of the air conditioning system 24, over the heat exchanger 72 of the heating system 26, and out of the enclosure 14 through the conditioned air duct connection 22. The illustrated second fan 80 is located in the flow path between the evaporator 62 and the heat exchanger 72 so that the second fan 80 pulls the air over the evaporator 62 and pushes the air over the heat exchanger 72.

The illustrated first and second fans 78, 80 are rotated by a common electric motor 82. The illustrated electric motor is located between the first and second fans 78, 80 so that the fans 78, 80 have a common axis of rotation extending in the forward rearward direction. The electric motor is preferably an AC electric motor of any suitable type.

As best shown in FIG. 7, the illustrated control system or controller 28 is operably connected to compressor 56 of the air conditioning system 24, the blower assembly 70, the fuel valve 76 and the igniter 75 of the heating system, the electric motor 82 of the air moving system, an a thermostat 84 located with the interior 52 of the recreational vehicle. The control system 28 is provided with suitable electronics to control operation of the compressor 56 to cool air passing over the evaporator 62 in a desired manner and operably connect the compressor 56 to AC power. In a cooling mode, operation of the compressor 56 is regulated by the thermostat 84 to obtain a desired air temperature within the interior of the recreational vehicle 12. The control system 28 is provided with suitable electronics to control operation of the blower assembly 70, the valve 76, and the igniter 75 in a desired manner and operably connects the components to AC power. The illustrated components 70, 76. 75 are operably connected to a 120 volt AC source but any other suitable type of source or power can alternatively be utilized. The illustrated burner igniter 58 is operably connected to a 110 volt source. The illustrated electromechanical valve 76 connects the burner assembly 64 with the gas inlet line 68 to selectively supply gas to the burner assembly 64. In a heating mode, when the combustion blower assembly 70 creates the desired pressure within the combustion chamber 66, the control system 28 passes voltage to the valve 76 to open the valve 76 and pass fuel gas to the burner assembly 64 and to the burner igniter 75 to start combustion of the gas at the burner assembly 64. The ignition is regulated by the thermostat 84 to obtain a desired air temperature within the interior of the recreational vehicle 12. The control system 28 is provided with suitable electronics to control operation of the motor 82 of the air moving system. Operation of the motor 82 is regulated by the thermostat 84 to obtain a desired air temperature within the interior of the recreational vehicle 12. The air flows generated by the motor 82 are different in heating and cooling modes. In a cooling mode, the controller 28 operates the motor 82 at a speed to provide a desired air flow over the condenser 58 and evaporator 62. In a heating mode, the controller 28 operates the motor 82 at a speed to provide a desired air flow over the heat exchanger 72. Suitable air flows are believed to be 550 CFM in the cooling mode and 400 CFM in the heating mode.

With reference to FIG. 8, when the HVAC unit 10 is in a heating mode to warm the air within the interior of the recreational vehicle 12, the controller 28 initiates the electric motor 82 to rotate the first fan 78 and draw air into first chamber of the enclosure 14 through the inlet 16 from the exterior of the vehicle 12 and forces the ambient air out of the first chamber of the enclosure 14 through the outlet 18 to the exterior of the vehicle 12. It is noted that the air is also drawn over the condenser 58 but the condenser 58 is not in operation at this time. The electric motor 82 also rotates the second fan 80 to draw air into the second chamber of the enclosure 12 through the return air duct connection 20 from the return air duct 50, forces the air over the heat exchanger and out of the second chamber of the enclosure 14 through the conditioned air duct connection 22 and into the conditioned air duct 54. It is noted that the air is also drawn over the evaporator 62 but the evaporator 62 is not in operation at this time. The controller also initiates the combustion blower assembly 70 which draws in air from the first chamber of the enclosure 14 to the combustion chamber 66. When the combustion blower assembly 70 creates the desired pressure within the combustion chamber 66, the control system 28 passes voltage to the valve 76 to open the valve 76 and pass fuel gas from the fuel source to the burner assembly 64 and to the burner igniter 75 to start combustion of the gas at the burner assembly 64. The combustion produces hot gases and/or air which is circulated through the heat exchanger 72 and the flue gas duct 74 to the exterior of the vehicle 12. The hot fluid passing though the heat exchanger 72 heats the air passing over the heat exchanger 72 in the second chamber. The ignition and air flow is regulated by the thermostat 84 to obtain a desired warm air temperature within the interior of the recreational vehicle 12.

When the HVAC unit 10 is in a cooling mode to cool the air within the interior of the recreational vehicle 12, the controller 28 initiates the electric motor 82 to rotate the first fan 78 and draw air into first chamber of the enclosure 14 through the inlet 16 from the exterior of the vehicle 12 and over the condenser 58 and forces the air out of the first chamber of the enclosure 14 through the outlet 18 to the exterior of the vehicle 12. The electric motor 82 also rotates the second fan 80 to draw air into the second chamber of the enclosure 12 through the return air duct connection 20 from the return air duct 50 and over the evaporator 62 and forces the cooled air out of the second chamber of the enclosure 14 through the conditioned air duct connection 22 and into the conditioned air duct 54. It is noted that the air is also forces over the heat exchanger 72 but the heat exchanger 72 is not in operation at this time. The controller 28 also initiates the compressor 56 of the air conditioning system 24 which initiates the cooling circuit to cool the evaporator 62. The cooled evaporator 62 cools the air passing over the evaporator 62 in the second chamber. The cooling circuit and air flow is regulated by the thermostat 84 to obtain a desired cool air temperature within the interior of the recreational vehicle 12.

The above described HVAC unit 10 can be advantageously produced with an installation envelope of about 24 inches by 24 inches by 24 inches and an installation weight of about 130 pounds. The above described HVAC unit 10 can also be advantageously produced with about 13,500 btu cooling and 31,000 btu heating.

It is apparent from the forgoing that the present invention provides an improved HVAC systems for recreational vehicles. The system 10 is compact and can be installed below the vehicle floor to provide both functional and aesthetic advantages. The system utilized common components for both the heating and cooling systems of the vehicle.

From the foregoing disclosure and detailed description of certain preferred embodiments, it is also apparent that various modifications, additions and other alternative embodiments are possible without departing from the true scope and spirit of the present invention. The embodiments discussed were chosen and described to provide the best illustration of the principles of the present invention and its practical application to thereby enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the present invention as determined by the appended claims when interpreted in accordance with the benefit to which they are fairly, legally, and equitably entitled. 

1. A heating, ventilating, and air conditioning unit for a recreational vehicle comprising, in combination: an enclosure having an ambient air inlet, an exterior outlet, a return air duct connection, and a conditioned air duct connection; an air conditioning system for cooling air; wherein the air conditioning system is located within the enclosure and includes a compressor, a condenser operably connected to the compressor, an expansion device operably connected to the condenser, and an evaporator operably connected to the expansion device and the compressor for cooling air entering the enclosure through the return air duct connection and exiting the enclosure through the conditioned air duct connection; a heating system for heating air; wherein the heating system is located within the enclosure and includes a gas-fired burner assembly located within a sealed combustion chamber and a heat exchanger operably connected to the combustion chamber for heating air entering the enclosure through the a return air duct connection and exiting the enclosure through the conditioned air duct connection; and a control system operably connected to the air conditioning system and the heating system to selectively heat or cool air entering the enclosure through the a return air duct connection and exiting the enclosure through the conditioned air duct connection.
 2. The heating, ventilating, and air conditioning unit for a recreational vehicle according to claim 1, further comprising a first fan located within the enclosure and drawing ambient air into the enclosure through the ambient air inlet, over the condenser, and out of the enclosure through the exterior outlet and a second fan located within the enclosure and drawing return air into the enclosure through the return air duct connection, over the evaporator and the heat exchanger, and out of the enclosure through the conditioned air duct connection.
 3. The heating, ventilating, and air conditioning unit for a recreational vehicle according to claim 2, further comprising an electric motor operably connected to both the first fan and the second fan for rotating both the first fan and the second fan.
 4. The heating, ventilating, and air conditioning unit for a recreational vehicle according to claim 2, wherein the second fan is located between the evaporator and the heat exchanger so that the second fan draws air over the evaporator and pushes air over the heat exchanger.
 5. The heating, ventilating, and air conditioning unit for a recreational vehicle according to claim 1, wherein the heating system is located above the air conditioning system within the enclosure.
 6. The heating, ventilating, and air conditioning unit for a recreational vehicle according to claim 1, wherein the ambient air inlet is located at an outboard end of the enclosure, the exterior outlet is located at a bottom of the enclosure, the return air duct connection is located at an inboard end of the enclosure opposite the outboard end, and the conditioned air duct connection is located at the inboard end and above the return air duct connection.
 7. The heating, ventilating, and air conditioning unit for a recreational vehicle according to claim 1, further comprising a flue gas outlet duct communicating the combustion chamber with an external environment, and a combustion electric blower for drawing combustion air into the combustion chamber and forcing flue gas into the outlet duct and out of the combustion chamber.
 8. The heating, ventilating, and air conditioning unit for a recreational vehicle according to claim 1, wherein the enclosure is sized to fit below a floor of the recreational vehicle.
 9. The heating, ventilating, and air conditioning unit for a recreational vehicle according to claim 1, further comprising a thermostat located within the recreational vehicle and operably connected to the controller to generally maintain air within the recreational vehicle at a desired temperature.
 10. A heating, ventilating, and air conditioning unit for a recreational vehicle comprising, in combination: an air conditioning system for cooling air; wherein the air conditioning system includes a compressor, a condenser operably connected to the compressor, an expansion device operably connected to the condenser, and an evaporator operably connected to the expansion device and the compressor for cooling air; a heating system for heating air; wherein the heating system includes a gas-fired burner assembly located within a sealed combustion chamber and a heat exchanger operably connected to the combustion chamber for heating air; a first fan positioned to draw ambient air in through an ambient air inlet, over the condenser, and out through an exterior outlet; a second fan positioned to draw return air in through a return air duct connection, over the evaporator and the heat exchanger, and out through a conditioned air duct connection; an electric motor operably connected to both the first fan and the second fan for rotating both the first fan and the second fan; and a control system operably connected to the air conditioning system, the heating system, and the electric motor to selectively heat or cool air entering the enclosure through the a return air duct connection and exiting the enclosure through the conditioned air duct connection.
 11. The heating, ventilating, and air conditioning unit for a recreational vehicle according to claim 10, wherein the electric motor is an AC motor.
 12. The heating, ventilating, and air conditioning unit for a recreational vehicle according to claim 10, further comprising an enclosure having the ambient air inlet, the exterior outlet, the return air duct connection, and the conditioned air duct connection therein and wherein the air conditioning system and the heating system are located within the enclosure.
 13. The heating, ventilating, and air conditioning unit for a recreational vehicle according to claim 12, wherein the ambient air inlet is located at an outboard end of the enclosure, the exterior outlet is located at a bottom of the enclosure, the return air duct connection is located at an inboard end of the enclosure opposite the outboard end, and the conditioned air duct connection is located at the inboard end and above the return air duct connection.
 14. The heating, ventilating, and air conditioning unit for a recreational vehicle according to claim 12, wherein the enclosure is sized to fit below a floor of the recreational vehicle.
 15. The heating, ventilating, and air conditioning unit for a recreational vehicle according to claim 10, wherein the second fan is located between the evaporator and the heat exchanger so that the second fan draws air over the evaporator and pushes air over the heat exchanger.
 16. The heating, ventilating, and air conditioning unit for a recreational vehicle according to claim 10, wherein the heating system is located above the air conditioning system.
 17. The heating, ventilating, and air conditioning unit for a recreational vehicle according to claim 10, further comprising a flue gas outlet duct communicating the combustion chamber with an external environment, and a combustion electric blower for drawing combustion air into the combustion chamber and forcing flue gas into the outlet duct and out of the combustion chamber.
 18. The heating, ventilating, and air conditioning unit for a recreational vehicle according to claim 10, further comprising a thermostat located within the recreational vehicle and operably connected to the controller to generally maintain air within the recreational vehicle at a desired temperature.
 19. A heating, ventilating, and air conditioning unit for a recreational vehicle comprising, in combination: an enclosure having an ambient air inlet, an exterior outlet, a return air duct connection, and a conditioned air duct connection; an air conditioning system for cooling air; wherein the air conditioning system is located within the enclosure and includes a compressor, a condenser operably connected to the compressor, an expansion device operably connected to the condenser, and an evaporator operably connected to the expansion device and the compressor for cooling air entering the enclosure through the return air duct connection and exiting the enclosure through the conditioned air duct connection; a heating system for heating air; wherein the heating system is located within the enclosure above the air conditioning system and includes a gas-fired burner assembly located within a sealed combustion chamber and a heat exchanger operably connected to the combustion chamber for heating air entering the enclosure through the a return air duct connection and exiting the enclosure through the conditioned air duct connection; a first fan positioned to draw ambient air in through an ambient air inlet, over the condenser, and out through an exterior outlet; a second fan positioned to draw return air in through a return air duct connection, over the evaporator and the heat exchanger, and out through a conditioned air duct connection; an electric motor operably connected to both the first fan and the second fan for rotating both the first fan and the second fan; a control system operably connected to the air conditioning system and the heating system to selectively heat or cool air entering the enclosure through the a return air duct connection and exiting the enclosure through the conditioned air duct connection; and a thermostat operably connected to the control system to generally maintain air within the recreational vehicle at a desired temperature.
 20. The heating, ventilating, and air conditioning unit for a recreational vehicle according to claim 19, wherein the ambient air inlet is located at an outboard end of the enclosure, the exterior outlet is located at a bottom of the enclosure, the return air duct connection is located at an inboard end of the enclosure opposite the outboard end, and the conditioned air duct connection is located at the inboard end and above the return air duct connection. 